From shott at stanford.edu Thu Jul 3 17:16:27 2008 From: shott at stanford.edu (John Shott) Date: Thu, 03 Jul 2008 17:16:27 -0700 Subject: System update .... Message-ID: <486D6BDB.5060606@stanford.edu> SNF Pquest Fans: Here is an update of what we have (and have not) done on the PlasmaQuest: Today, Elmer and Mike did a full chamber clean and wipe down. At the same time, they shut off the turbo to pull out the gate valve. They removed quite a collection of broken wafers and fragments from the gate valve and the screen on top of the turbo valve. At the same time the main O-ring seal of the gate valve was replaced. To test that the gate valve is now closing fully, the system was put in a state where the main gatevalve was shut but the chamber and the loadlock were at atmosphere. If the gate valve were leaking, the turbo would have been at a high pressure and the load lock lid would have been unable to be manually lifted. As a result of this test, we believe that the gate valve is closing fully. After the wet clean, the chamber was cleaned with an oxygen recipe for 6000 seconds. Any folks doing any etching will likely want to make sure that they have seasoned the chamber properly to meet their needs and to check etch properties carefully. What has not yet been done: The ferrofluidic rotary seal that controls the wafer up/down clamping motion is showing some (but not yet severe) leakage. When I was observing system pressure with the gate valve shut, the rate of rise was higher when the clamp was either going up or down than it was when the clamp was either fully open or fully closed .... that is, the rotary feed through seems to leak more when it is in motion that when it is not in motion. This is fortunate because the rotary feedthrough is not in motion during etching .... only when the wafer is being loaded or unloaded. Unfortunately, this is not an easy part to acquire. It currently has a 4 week lead time from Nexx and one of the 2 manufacturers of the feedthrough can do no better. While I am still trying to contact the other manufacturer, we may have to wait on this. Hopefully, this seal will hold on during that time and allow useful work to be done as it does not appear to be a severe leak at the moment. The other part on which we are waiting is the special "soft and squishy" (AKA Shore A durometer 40) O-ring that is used for the backside helium seal. We expect those to be delivered early next week. At this point, we believe that helium backside leakage with the existing O-ring is within tolerable limits. Let me know if you have any questions and I'll try to do my best to answer. If there are process questions, of course, either Jim Kruger or Jim McVittie are your best local sources of information. Happy processing, John From jimkruger at yahoo.com Tue Jul 8 17:18:29 2008 From: jimkruger at yahoo.com (jim kruger) Date: Tue, 8 Jul 2008 17:18:29 -0700 (PDT) Subject: PQuest update 7-8-08, jimkruger Message-ID: <758287.38585.qm@web38903.mail.mud.yahoo.com> PQuest update 7-8-08 My belief is that there are two issues with PQuest at the moment. Most serious is a varying air leak at the mechanical rotary feed-thru that raises and lowers the wafer clamp. The feed-thru is FerroFluidic, using fluorocarbon based oil for service in the plasma chamber. Repair is likely not feasible. Estimated delay for a replacement part is 4 weeks (from today, order placed). The second problem is a varying leak across the gate valve when closed. This does not affect the system in normal operation but interferes with leak-up tests used to measure the feed-thru leak. If the leak is significant, the pressure ?zero? will be affected so that very low pressure recipes (GaAs is at 2 mTorr) may run with a significant pressure error. The more serious problem is the addition of an uncertain flow of air to the recipe. Recent experience with GaAs has reported rapid loss of resist as well as inability to strip some areas of resist (encapsulated by ?GaAs oxide? or perhaps Boron Oxide from the BCl3?). I recommend that recipes not involving a significant deliberate flow of Oxygen not be run until repairs can be done. Even a qualification run may not be useful since the leak appears to vary with every motion of the wafer-lift clamp. For the record, the historical ?good? leak-up rate is 1 to 2 mTorr/minute, measured over 3 to 5 minutes. Currently, I see as much a 10 times that, but with high variation due to the varying leak across the "closed" gate valve. A test recipe demonstrating the 2 issues is ?_TST1?. Bottom line: expect about a 4 week delay before Oxygen free etching can be restored. jimkruger From shott at stanford.edu Thu Jul 10 09:11:22 2008 From: shott at stanford.edu (John Shott) Date: Thu, 10 Jul 2008 09:11:22 -0700 Subject: Better news: ferrofluidic seal!!! Message-ID: <487634AA.7070802@stanford.edu> Pquest Community: I believe that we have located an appropriate replacement ferrofluidic feed through that be available much sooner than the originally advertised 4-week delivery time. I'm preparing a purchase order for it as we speak and believe that it should arrive tomorrow. While it may arrive too late in the day for Elmer and Mike to install it, I believe that Cesar will be back in town over the weekend and will ask him to try to effect the replacement of this important component. If you have any questions, please let me know. Thanks, John From eenriquez at snf.stanford.edu Tue Jul 15 15:25:22 2008 From: eenriquez at snf.stanford.edu (Elmer Enriquez) Date: Tue, 15 Jul 2008 15:25:22 -0700 Subject: Update Message-ID: <487D23D2.9050904@snf.stanford.edu> Tried to install new ferrofluidic seal but it was the wrong size (body is too short). We opened the gate valve and found wafer chips on the o-ring. We replaced the o-ring and retaught the valve. Also replaced the backside He cooling o-ring. Ran an O2 plasma for 1 hour. From faraon at stanford.edu Wed Jul 23 09:14:23 2008 From: faraon at stanford.edu (Andrei Faraon) Date: Wed, 23 Jul 2008 09:14:23 -0700 Subject: pquest free today 1pm - 3:30pm Message-ID: <28d3ece90807230914s35aa587dk64df9cfc451bf334@mail.gmail.com> -- Andrei Faraon Stanford University, Applied Physics 316 Via Pueblo Mall Stanford, CA, 94305 Mobile: 650 714 7881 Office: 650 723 2279 www.stanford.edu/~faraon -------------- next part -------------- An HTML attachment was scrubbed... URL: From lwchang at stanford.edu Thu Jul 24 12:40:51 2008 From: lwchang at stanford.edu (Li-Wen Chang) Date: Thu, 24 Jul 2008 12:40:51 -0700 Subject: Aluminum etching in PQuest Message-ID: <8ab79e460807241240j100d6912i6090b23bae00086@mail.gmail.com> Dear PQuest users, I'm wondering if anyone has done aluminum etching in PQuest. My sample is gold contaminated and can not go in p5000. I'd really appreciate if someone has a starting recipe for Al etching. Thanks, Li-Wen -------------- next part -------------- An HTML attachment was scrubbed... URL: From jiazhu at stanford.edu Tue Jul 29 12:00:08 2008 From: jiazhu at stanford.edu (jiazhu at stanford.edu) Date: Tue, 29 Jul 2008 12:00:08 -0700 Subject: GaAs etching using silica as mask Message-ID: <20080729120008.cngvf9fcg040osks@webmail.stanford.edu> Hi PQuest Users, I am wondering whether anyone has any experience on GaAs etching using silica (SiO2) as mask before? Any information regarding this will be very helpful! Thanks. regards, Jia